This example project shows how to build and run an ultrasonic presence detection application using the Chirp SonicLib sensor API. This is a companion document to AN-000214 Presence Detection, and AN-000226 CH201 Ultrasonic Presence Detection Reference Design User Guide. Application note AN-000214 focuses on the test results of the embedded static target rejection algorithm and the presence detection algorithm used in the CH201 presence detection evaluation module. Application note AN-000226 is a user guide for the CH201 ultrasonic presence detection reference design module. The Presence Detection example is a simple C application that demonstrates the use of motion detection to determine the presence of people and objects. The application uses the Chirp SonicLib API functions to initialize, configure, and operate one or more ultrasonic sensors. It uses special sensor firmware along with API functions which specifically support presence detection.